What is Sinus infection ?

Sinus infections are caused by infections from a pathogenic microorganism (virus, bacterium, or fungus), which grows within a sinus and causes intermittent blockage of the sinus ostium.

• Sinusitis is inflammation of the air cavities within the passages of the nose. Sinusitis can be caused by infection, but also can be caused by allergies and chemical or particulate irritation of the sinuses.

• Bacterial infection of the sinuses is suspected when facial pain, pus-like nasal discharge, and symptoms that persists for longer than a week and are not responding to over-the-counter nasal medications.
• The most common symptom of sinusitis, and often the most unpleasant, is pain. You have several different sinuses above and below your eyes, and behind your nose. Any of these can hurt when you have a sinus infection.

• Inflammation and swelling in the sinuses causes them to ache with a dull pressure. You may feel pain in your forehead, on either side of your nose, in your upper jaws and teeth, or between your eyes.
• Pain from a sinus infection is no fun, and the nasal discharge isn’t great either. When you have a sinus infection, you may need to blow your nose often because of a greenish-yellow discharge. This comes from your infected sinuses and drains into your nasal passages.
  The discharge may also bypass your nose and flow down your throat. You may feel tickle or an itch down the back of your throat. This is called postnasal drip.
• The relentless pressure and swelling in your sinuses can reverberate throughout your skull and leave you with a massive headache. The pain can also show up in places you might not expect. Sinus pain can give you earaches, toothaches, and pain in your jaws and cheeks.
• Sinus headaches are often at their worst in the morning because fluids have been collecting all night long. You may also experience a worsening of the headache when the temperature of your environment changes suddenly.

Read about sinus symptoms : http://sinusitisinfection.blogspot.in/2014/03/symptoms-and-home-remedies-for-sinus.html